In a typical check printing system the operator at a client (terminal) directs the printer to print a check, or a job comprising a number of checks. If a printed check is defective for any reason, the operator may destroy it and print another. A problem is that the operator may fraudulently print duplicate checks, and current printers do not have the capability to detect and prevent this, although some efforts have been made.
One method of dealing with the problem of jammed checks is to provide the printers with a "jam recovery" feature that allows a duplicate check to be printed following a printer jam. This feature is manually enabled by a system administrator who oversees the operator, or by an authorized operator. The problem is that in some cases, even though a jam occurred, the check is printed and is of acceptable quality. In this system, a certain amount of trust by the system administrator or the operator is required.
An example is the Xerox Model 4197 system as shown in FIG. 1. As shown, step 1 shows the normal print command issued from the client 10 to the printer 11. After a check is printed normally, information about the job is recorded in the non volatile random access memory (NVRAM) 12 as a transaction record. The format of the record is shown as follows:
______________________________________ User ID 1 byte Time Stamp 6 bytes Check No. 3 bytes Payee 27 bytes Amount 5 bytes MICR-Line 22 bytes Status 1 byte ______________________________________
In the event of a jam, as shown in step 2, a notification is sent from the printer to the client. Step 3 is a command issued from the client 10 to the system administrator 13 or equivalent (which could even be a telephone call) to enable jam recovery for duplicate printing. The system administrator, step 4, clears the NVRAM entry (or enables the entry, in case it is disabled) so that the operator can print a duplicate check. The operator is trusted to void the initial check either by destroying it or by void stamping it. This is shown in Step 5. It is at this step that the operator can misappropriate a check. What is needed is a printer model with enhanced cryptographic hardware and techniques built into the printer to prevent this possibility.